The present invention relates to a sputtering target capable of performing deposition on a wafer or a substrate during sputtering at a stable deposition speed.
The speed of forming a thin film on a wafer or a substrate during sputtering is not constant, and changes with the advancement of the erosion of the target. Normally, this change is a functional change associated with the target life, and deposition of a fixed film thickness is performed throughout the target life by functionally changing the sputtering time of the deposition device according to the target life. Generally, the sputtering time change program that is once set is valid even when the target is replaced, and there is no need to make fine adjustments or the like for each target.
Nevertheless, with a Ta target, variation in the deposition speed for each target throughout the target life is significant and, therefore, it has become recently known that there are many cases where it is necessary to re-input the sputtering time program midway during the target life, or, in certain cases, to replace the target ahead of time before reaching the end of the target life.
Re-programming of the sputtering time midway during the target life will significantly inhibit the production efficiency, and replacing an expensive material such as a Ta target midway through the target life will considerably increase the manufacturing cost. Thus, this is becoming a major problem at semiconductor production sites.
There have been previous references to the influence of the Ta target material on performance during sputtering, and it has been suggested that various impurities, gas components, plane orientation, surface roughness and crystal grain size affect the uniformity and generation of particles (for instance, refer to Patent Document 1). In addition, it has also been suggested that the plane orientation and its variation, crystal grain size and impurities affect the uniformity of a tantalum nitride film (for instance, refer to Patent Document 2).
In particular, Patent Document 1 describes that the deposition speed can be improved by selectively increasing the plane orientation of {111}, {200}, {211} having high atom density on the sputtered surface, and the uniformity can be improved by suppressing the variation of the plane orientation. Nevertheless, the current status is that there is no particular knowledge regarding the influence on the fluctuation of the deposition speed throughout the target life.
[Patent Document 1] Japanese Patent Laid-Open Publication No. H11-80942
[Patent Document 2] Japanese Patent Laid-Open Publication No. 2002-363736